<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
        .inner {
            width: 1vmin;
            height: 1vmin;
            background: blue;
        }
    </style>
</head>
<body>
<div class="outer">
    <div class="inner"></div>
</div>
</body>
</html>

